Japan opened an international whaling conference Tuesday by blasting a boycott by dozens of anti-whaling nations, saying their absence would block much-needed reforms of the International Whaling Commission.

The conference, which Japan called as part of its push to resume commercial whaling, was attended by only about 35 of the 72 members of the IWC. The boycotters included anti-whaling countries Britain, Australia and the United States.

The boycott illustrates the intense divide over Japan's whaling program as anti-hunt protesters have clashed — sometimes violently — in recent days with Japanese whaling ships in the South Pacific.

Minoru Morimoto, Japan's IWC representative, told the conference that the boycott made it "almost impossible" to have a worthwhile discussion on reforming the IWC, which Japan argues should manage commercial whaling rather than banning it outright.

A global moratorium on commercial whaling has existed since 1986, but Japan kills hundreds of whales each year under a scientific whaling program conducted within the commission's rules. The meat from the program is sold as food.

Tokyo maintains that whaling is a national tradition and a vital part of its food culture, and argues that whale stocks have sufficiently recovered since 1986 to allow a resumption of limited hunts of certain species.

The conference is taking place amid stepped-up clashes between whalers and protesters on the high seas. On Monday, a Sea Shepherd protest ship collided with a Japanese whale spotting ship, the Kaiko Maru. Both claimed they were rammed by the other. There were no injuries.

New Zealand Conservation Minister Chris Carter rebuked both sides for "stupid playground behavior," and later spoke to Sea Shepherd founder Paul Watson to warn him against carrying out threats to ram Japanese ships.

"Sea Shepherd's protest has gone too far," Carter said on New Zealand's National Radio. "Any further action on the part of Captain Paul Watson risks the loss of human life, and severe damage to the cause of whale conservation."

Many environmental groups claim Japan's research program is merely an excuse to keep Japan's tiny whaling industry alive. Opponents also allege that Japan provides aid to friendly nations in the IWC in exchange for their support.

Representatives at the conference denied their support had been purchased with Japanese assistance.

"We are not a whale-hunting country, but the matter of resources within our sea is very important to us," said Cedric Liburd, the fisheries minister of St. Christopher-Nevis. "No country can buy our vote."

Liburd and other conferees said the IWC had become so polarized by the conflict between pro- and anti-whaling nations that it was unable to fulfill its function, and that it needed to be revamped.

"For many years the IWC has been at an impasse," said Turid Rodrigues Eusebio, the representative from Norway, a leading pro-whaling country.

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